<!DOCTYPE html>
<title>adoptedStyleSheet - Add and remove the same sheet with modifications</title>
<link rel="help" href="https://drafts.csswg.org/cssom/#extensions-to-the-document-or-shadow-root-interface">
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<div id="target">This text should be green</div>
<script>
  const sheet_a = new CSSStyleSheet();
  sheet_a.replaceSync("#target { color: red; }");
  const sheet_b = new CSSStyleSheet();
  sheet_b.replaceSync("#target {}");

  test(() => {
    document.adoptedStyleSheets = [sheet_a, sheet_b];
    assert_equals(getComputedStyle(target).color, "rgb(255, 0, 0)");
  }, "Add the two sheets. Text should be red.");

  test(() => {
    document.adoptedStyleSheets[1] = sheet_a;
    document.adoptedStyleSheets[0] = sheet_b;
    assert_equals(getComputedStyle(target).color, "rgb(255, 0, 0)");
  }, "Flip the two sheet. Still red.");

  test(() => {
    sheet_a.cssRules[0].style.color = "green";
    assert_equals(getComputedStyle(target).color, "rgb(0, 128, 0)");
  }, "Modify the color declaration. Should now be green.");
</script>
